1. Field of the Invention
This invention relates to a wood lathe, and more particularly to a wood lathe, which includes a stepless speed-adjusting unit that is operable to adjust the rotational speed of a workpiece.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional wood lathe 10 is shown to include a table 11, a fixed seat 12, a coupling rod 13, a workpiece-holding unit 14, a blade unit 15, and a driving unit 16. The table 11 has a first end 111 and a second end 112. The fixed seat 12 includes a right housing 121, a partition 122, and a left housing 123. The partition 122 is disposed between and is connected removably to the right and left housings 121, 123. The coupling rod 13 is disposed fixedly on the table 11, and has a first end 131 that extends through a bushing 1212 on the right housing 121 of the fixed seat 12, and a second end 132. The workpiece-holding unit 14 includes an output shaft 141 that extends through a bearing 1211 on the right housing 121, a left clamping element 142 that is bolted to the output shaft 141, a sliding member 143 that is sleeved movably and that is locked releaseably on the second end 132 of the coupling rod 13, and a right clamping element 144 that is mounted rotatably on the sliding member 143. The left and right clamping elements 141, 144 press respectively against two end surfaces 172, 171 of an elongated wood workpiece 17 so as to clamp the workpiece 17 between the left and right clamping elements 141, 144, thereby permitting synchronous rotation of the workpiece 17 and the output shaft 141. The driving device 16 includes a motor 161 that is disposed between the left housing 123 and the partition 122, a stepped driving wheel 162 that is sleeved fixedly on a motor shaft of the motor 161, a stepped driven wheel 163 that is sleeved fixedly on the output shaft 141, and an endless driving belt 164 that is trained on the driving wheel 162 and the driven wheel 163.
When it is desired to change the rotational speed of the output shaft 141 and the workpiece 17, the left housing 123 is removed from the partition 122 and the right housing 121 so that the position of the belt 164 can be adjusted relative to the driving wheel 162 and the driven wheel 163. Subsequently, the left housing 123 is mounted back onto the partition 122 and the right housing 121. As such, it is time-consuming to adjust the rotational speed of the workpiece 17. Furthermore, the lathe 10 cannot be used to rotate a second workpiece that is shaped as a ring plate.
An object of this invention is to provide a wood lathe, which includes a stepless speed-adjusting unit that can be adjusted with relative ease to change the rotational speed of a workpiece.
Another object of this invention is to provide a wood lathe, which can be used to rotate a workpiece that is shaped as a ring plate.
According to this invention, a wood lathe has a driving device, which includes a driving pulley unit disposed around a rotating inner rod, a driven pulley unit disposed around a first output shaft, a V-belt unit trained on the driving and driven pulley units, and a speed-adjusting unit. The first output shaft is used to rotate a first workpiece that is shaped as a straight rod. When a rotary knob is rotated, a movable inner half of the driven pulley unit moves toward or away from a fixed outer half of the driven pulley unit so that the V-belt unit moves a movable outer half of the driving pulley unit away from or toward a fixed inner half of the driving pulley unit. As such, the position of the V-belt unit can be adjusted relative to the driving and driven pulley units to change the rotational speed of the first output shaft.
Preferably, the lathe further has a workpiece-holding unit that includes:
a bearing tube member disposed fixedly on a table;
a second output shaft parallel to the first output shaft and having an externally threaded first end with a reduced outer diameter to define a shoulder, and a second end, the second output shaft being journalled within the bearing tube member and being adapted to extend through a second workpiece that is shaped as a ring plate;
a driving gear sleeved fixedly on the first output shaft;
a driven gear sleeved fixedly on the second end of the second output shaft;
a toothed endless belt trained on the driving and driven gears so as to transfer rotation of the first output shaft to the second output shaft; and
a nut engaging threadably the first end of the second output shaft so as to be adapted to lock the second workpiece between the nut and the shoulder of the second output shaft.